1. Field of the Invention
The present invention relates to an improvement of a removable cap attached, in an insertion manner, to a front-end portion of a writing instrument such as marking pens, markers and the like so as to prevent ink from evaporating from the writing instrument.
2. Description of the Prior Art
Removable caps attached to the writin instruments such as marking pens, markers and the like are employed to prevent ink from evaporating from the writing instruments, to protect pen-point portions of the writing instruments from damages and to prevent the writing instruments from smudging other items with ink thereof. Consequently, the caps are constructed of resin-molded articles which are excellent in properties of preventing ink from evaporating from the writing instruments. For example, as shown in FIGS. 5 to 8, a conventional removable cap 12 attached to a writing instrument in an insertion manner is provided with an axial bore 15 in which an inner cylindrical portion 13 is integrally formed with a rear-end wall portion or closed end portion of the cap 12 a front end of which is open. Since the conventional cap 12 having the above construction is completely closed at its rear end, there is a fear that the cap suffocates infant's bronchi when the infant swallows the cap whole.